Integrated circuit devices containing several types of functional circuit are sometimes required to handle a plurality of voltage levels. Such devices are often known as multi-voltage level devices. Multi-voltage level devices contain a high-voltage circuit driven by a relatively high voltage power supply and a low-voltage circuit driven by a relatively low-voltage power supply. Multi-voltage circuits include but are not limited to voltage level shifters (VLS), isolation cell, retention registers, always on logic and similar components.
Power consumption of integrated circuits may be reduced and efficiencies may be increased by reducing operating voltages of the integrated circuits. Some circuits are more amenable to lower operating voltages than others. Where integrated circuits within a system operate at lower voltages, conflicts or contention may arise between the circuits. These conflicts and contention can be alleviated by level shifting the operating voltage of part of the circuits to higher voltage. But level shifting may introduce delays.
Technology scaling reduces the delay of circuit elements, enhancing the operating frequency of an integrated circuit (IC) device. The density and number of transistors on an IC are increased by scaling the feature size. By utilizing this growing number of available transistors in each new technology, novel circuit techniques can be employed further enhancing the performance of the ICs beyond the levels made possible by simply shrinking.